I did this, and now I can log in, but only after I reset the password on the mailboxes. Also, all the mailboxes I've tried so far are empty. Any idea why?

EDIT: I noticed on the mailbox folders I log in, there is a new Maildir folder with cur, new and tmp which are empty. The ones I haven't logged in (or change the password) do not have the Maildir folder, just cur, new and tmp. How do I change this so that the emails don't go into this new Maildir folder and the users can see their old emails?